Telephone system and automatic switch suitable for use therein



P 1941- J. sT. c. w. GRAHAM 2,255,831

TELEPHONE SYSTEM AND AUTOMATIC SWITCH SUITABLE FOR USE THEREIN Filed Jan. 8, 1958 2 Sheets-Sheet 1 INVENTOR JOHN 52' CLARE WILL/AM GRAHAM ATTY 1- 6, i941- J. ST. c. w. GRAHAM 2,255,881

TELEPHONE SYSTEM AND AUTOMATIC SWITCH SUITABLE FOR USE THEREIN Filed Jan. 8, 1938 2 Sheets-Sheet 2 FROM TO OTHER EXCHANGE suas INVENTO'R JOH .CLARE WILL/AM GRAHAM ATTY Patented Sept. 16, 1941 UNITED STATES PATENT OFFICE I 2,255,881- TELEPHONE SYSTEM A D AUT MATIC SWITCH SUITABLE FQR USE THEREIN John St. Clare William Graham, Liverpool, England, assignor to Associated Telephone & Telegraph Company, Chicago, 111, a corporation of Delaware 27 Claims.

The present invention relates to telephone systems and automatic switches suitable for use therein and is more particularly concerned with switches of the spring-driven escapement type which may be electrically rewound by power supplied from a distant point. The object of the invention is to provide an improved construction of spring-driven escapement type switch suitable for operation with very small currents of the order of 2 milliamperes. With such a switch it is possible for a plurality to be operated satisfactorily over a long line in a parallel circuit and the invention contemplates this arrangement as part of a telephone system.

According to one feature of the invention in a stepping switch suitable for operation over a telephone line in parallel with a plurality of similar switches the drive is effected from a source of stored energy under the control of signals from a distant point, the energy storage being subsequently returned to its original level by the transmission of electrical energy from the distant point for an appreciably longer period than that occupied by the transmission of the control signals.

According to another feature of the invention in a telephone system having a plurality of parties associated with a common line extending to an exchange from which the setting up of all connections is effected the various parties are associated with the line by means of stepping switches arranged to be spring driven under escapement control in response to setting impulses from. the exchange and to be rewound after use in response to current subsequently supplied from the exchange.

The invention will be better understood from the following description of one method of carrying it into effect, reference being had to the accompanying drawings comprising Figs. 1-3. Figs. 1 and 2 are respectively elevation and plan views showing diagrammatically sufiicient of the mechanism of a spring-driven escapeinent type switch to enable its operation to be understood, while Fig. 3 shows the circuit arrangements of the equipment of one party on a party line in a telephone system making use of the switches illustrated in Figs. 1 and 2.

It should be explained that the circuit of Fig. 3 is substantially identical with that disclosed in O. A. Pearces application No. 143,653, filed May 20, 1937, which made use of directly operated stepping switches at the various subscribers stations on the party line, and only such changes have been made in the present disclosure as are required in View of the use of the spring-driven escape-merit type switches constructed according to Figs. 1 and 2. It will be convenient to d scribe first the circuit shown in Fig. 3 in order that a clear understanding of the functions of the mechanism may be obtained.

Referring to Fig. 3, it will be appreciated that a two-eonductor line A and B extending from the exchange is provided per party line group of subscribers, the apparatus for each subscriber being connected across the line, it being assumed firstly that a plurality of individual subscribers, as against groups, are connected thereto.

In addition to the ordinary telephone, each subscriber is provided with an indicator, for instance of the eyeball type; which may be accommodated in a position where it will be easily seen by the subscriber. The individual switching equipment also includes a gas discharge device such as a neon tube and two spring-driven escipemen-t devices of the tybe shown in Figs. 1 an 2.

At the main exchange a switching unit is introduced between the line and the usual line and cut-off relay assembly, and this unit includes a stepping switch which serves to count or control the impulses received or transmitted on calls between the main exchange and the group of subscribers. British specification No. 452,038 discloses a type of unit which could be simply modified to operate with the apparatus required in the system about to be described.

It will be understood that each subscriber is provided with two spring-driven escapement type switches designated F and C in the drawing which are wound up at the conclusion of each call by the operation of the magnet FW and CW by current supplied from the exchange. It might be feasible for the winding mechanisms to be combined so that one magnet would wind up both mechanisms but in the present example separate winding magnets are assumed to be provided. Moreover, as an alternative the escapemeht magnet might be arranged to efiect the rewindin'g in response to a mechanical ghange in the members controlled by it's armaure.

Assuming that the line serves ten subscribers, each switch will have 12 positions, the first being ahorne position, the second being reserved for a purpose to be described later, while of the remaining 10 positions a different position is allocated to each subscriber. Two cams are mounted on the driving shaft, one of which serves to operate off-normal springs while" the other is When a subscriber calls, the'switch-hook con: r V

tacts SH l loop the A and B leads to the main exchange. The exchange equipment not shown, but in view of the disclosure of the abovementioned specification it will 'sufiicefor the purpose of this description tosay that an earthed relay shunted by a rectifieris. connected to the A leg by way of a changeover contact while another relay connected to battery connected to the B leg by way of a changeover contact On completion of the loop, the relay connected to battery operates and locks in a local circuit while the'earthed relay does not operate in this condition' since it is shuntedbyfthe rectifier in a conductive direction. The'changeover contacts on the B leg at the exchange are now'operated and high potential pulses of the order of 120 volts positive toearth are thereupon connected to the B wire and extended to all the party line subscribers equipmentin parallel. In response toeach pulse the neontubes NT associated with all the stations on the line are caused to strike 1 and bring about the operation of the escapement magnets F since'the rectifiers MBA in series therewith are in the Iconductive direction while the rectifiers MRC in parallel are in the nonconductive direction. Rectifier MRB is nonconductive to positive pulses so that the C magnets do not respond atthistime. I

Y On the first pulse therefore, the F magnets are energised in series with the indicators MPI so that all switches step from the home position 1 to position 2 while the indicators which are preferably of the eye-ball type operate to give a visual indication of the engaged condition of the line. The oif-nor'rnal springs F(N) of each F switch are now operated and at, contacts F( N) I short-circuit the indicators'MPI and disconnect the rectifiers MRC from. across the F magnets, while at the same time contacts F(N)2 disconnect the calling loop from the line and prevent other subscribers frombreaking ,in on the connection if" they attempt to originate a call. The indicators are quicker to operate than the magremain operated throughout the call to give a busy indication.

On the second pulse the i to position 3 where selecting contacts FI and F2 1 on the switch associated with subscriber No. 1 are operated, but if he is not the one who hasoriginated the call there will be no lojop extended.

across the line by way of his instrument since 1 his switch-hook contacts SI-Il will not be operated, and accordingly the pulses from the exchange continue; If subscriber No. 4 has originated'the call, when all F switches moveto position 6 on receipt of the fifth pulse, a loop is connected across the line by way of contacts F2 of the switch associated with subscriber No. 4, dial impulse contacts IMP, his telephone instrument,

contacts FI and the switch-hook contacts SI-Il, and accordingly the fifth positive pulse applied to I the, 13 line finds a circuit over'this loop to the A 1 line and thus operates the earthed relay con 3 nected thereto in the main exchange since the rectifier; bridged across this relay is. now "non F switches are stepped conductive. In response to the operation of this relay further transmission of pulses is stopped. All F switches will therefore be set to position 6 and as only F switch No. 4 closes switching springs in this position, only No. 4 telephone instrument will be bridged across the line. Meanwhile at the main exchange another switch will have stepped in synchronism with the F switches to select the meter of No. 4 subscriber or alternatively in the case of a manual exchange, indicate to the operator the number of the subscriber who is calling.

. At, the main "exchange the A and B leads are now connected to the ordinary line relay equipment to prepare the automatic equipment for receiving the dialled digits or alternatively in the 1 case of a manual exchange to give a calling signal tothe-operator. The subscriber now repeats the number to the operator or alternatively dials the digits required to obtain the desired connection. The visual engaged indication will be maintained throughout the call and it is impossible for any othersubscriber in the'group to' listen in to the conversation.

At the end of the conversation when the calling.

switches are released step by step until the home position is reached that is, the. controlling cams have made a complete revolution, whereupon the off-normal contacts F(N)l and F(l l) 2 are restored. Accordingly the rectifier MRC is-now bridged across each magnet F and acts as'a ShOItrCiI'CUit between the break period of the pulses to prevent the F switches from being released past the home position. release .pulses' transmitted is arranged to be at least equal to the maximum number required to home the F switches from any position, and when the sending out of these pulses is completed the Fswitch magnets will restore.

.A plurality of high potential pulses of the order of 120 volts negative to earth are now transmitted over the B line thus causing each neon tube NT to flash again on the extension-of each V 3 nets F and as they are of the polarised type, they r pulse-while each rectifier MRB Will now be in a conductive direction and each rectifier MBA in a V V non-conductive direction. Ihe C switches associated with each subscriber therefore respond and on the receipt of the first negative pulse thebusy indicators MPI are causedto reset and remain in this. normal condition until a positive pulse is again applied on initiation orreception of a further call. On receipt of further pulses the C switches are advanced step by step completely round to the home position where the magnets lock owing to the ,short-circuiting effect ofthe rectifier MRD until the'train of negative releasing pulses ceases.

' Immediately the C switches arrive at the home position, cam springs CWC are closed to connect the winding magnets CW to the B line. Owing to the presence of. the metal rectifier MRF however the winding magnets CW are not responsive to the remainder of the highpvoltage negative releasing pulses. Similarly in connection With,v the F switches it will be understood thatwhen these.

arrive. at the home position, cam springs FWC are operated to connect the winding magnets FW to the. A line;

On the cessation of the high voltage negative releasing pulses, further. circuit changes take place at thevm'ainexchange to bring about the :connection to-the A and B leads; of a low voltage The number of positive battery, the potential of which is not sufiicient to cause the neon tube on the B leads to strike so that the magnets F and C cannot be energised. The winding magnets 01' all F and C switches are thereupon energised in a self-interrupting circuit by way of the magnet interrupter contacts FWI and CW] respectively and by means of a ratchet drive operating through a reduction gear they wind up the spring driving the escapement mechanisms. Alternatively should it prove more convenient to use the normal high voltage battery for winding, all winding magnets could be connected to the A line and the high potential applied to this line alone. When the escapement mechanisms are fully wound the cam springs FWC and CWC respectively open to disconnect the winding circuit, and when all switches have been rewound the earth connection is removed from the A and B lines and accordingly the equipment at the main exchange restores to normal in readiness fora further call.

Considering now an incoming call to one of the group of subscribers, when the final selector or operator selects the desired party a single high potential positive impulse is delivered initially to the B line to cause the indicators MP1 to show the engaged signal and at the same time the F switches are moved to position .2 in which no contacts are operated apart from the onnormal contacts. of high negative potential indicative of the wanted subscriber are now applied to the B line, to which the C switches respond, while the indicators MPI are prevented from resetting by the short-oircuiting-effect of contacts F(N) I. On the completion of the train of pulses, switching contacts Cl and 02 on the switch associated with the wanted subscriber are operated whereupon the earthed bell of this subscriber is connected by way of contacts 8H2, condenser QA and contacts C2 and F2 to the A line. Ringing current is now applied over the A line from the main exchange and the wanted subscribers bell only will ring and when he removes his receiver, contacts SH! and SHZ operate to disconnect the bell and connect a loop across the line thereby tripping the ringing at the exchange. Conversation now proceeds.

At the conclusion of the call when the subscribers hang up, a plurality of high voltage positive pulses are first extendedover the B line to home the F switches, and this is followed by a plurality of high voltage negative pulses to home the C switches and restore the indicators. In this case it will be noticed that the indicators are restored by the next negative impulse after the C switches reach the home position when the short-circuiting earth extended over contacts C(N)I is removed. With all F and C switches in the home position, all winding magnets FW and CW are connected in circuit over the cam springs FWC and CNC to perform the re-winding operation in the manner already described.

In the case of interconnection being desired between subscribers on the same line, the calling subscriber removes his receiver in the usual manner, and when he has obtained connection with the exchange as explained, he dials a special number consisting of a number characteristic of the Wanted subscriber prefixed by an additional digit or digits which give access to a revertive calling "switch in themain exchange. The calling subscriber then :hangs up hisreceiver and the revertive equipment transmits the re- -A number of selecting pulses quired number of high voltage pulses over the B line to set all C switches to the position of the wanted party. The indicators which have been set tothe busy condition during the finding operation of the calling party are unaffected during the operation of the C switches since they are short-cir-cuited by the ofi-normal contacts F(N) l of each switch F. At the end of the negative pulse train the C switch associated with the wanted subscriber closes its contacts Cl and C2 and thereby extends the earthed bell of his instrument .to the A line to which ringing current is applied from the exchange equipment. As the bell of the calling subscriber is also connected to the line during this condition since his receiver is restored, both bells are rung in parallel. When both subscribers remove their receivers, their telephones are connected in parallel to the main exchange and conversation may proceed. On completion of the conversation, the usual series of high voltage positive and negative pulses are extended to home the F and C switches and this is followed by the self-interrupted driving of the winding magnets in order to prepare the switches for the next call.

It will be noted that during conversation the earthed switching equipment is isolated from the line by means of the neon tube NT while similarly the winding magnets are isolated through the opening of the cam contacts and therefore the standard of speech transmission provided for the party line subscriber is the same as that provided for other subscribers on the exchange who are individually connected.

Although in the example described separate F and C switches are assumed to be provided for each subscriber, it is possible that circumstances will arise where certain of the subscribers premises are adjacent to each other, making it feasible for, say, two or three subscribers instruments to be controlled from the same mechanism. In these circumstances it will be necessary to equip the F and C switches with additional cams and spring sets operable in different positions of the switches as determined by the respective subscribers numbers, and from the switching unit connecting wires will radiate to the various instruments in the group.

With this arrangement however some four or five wires will be required to be extended from the switching mechanism to each subscribers telephone and in order to reduce the number of these conductors it might be preferable to dispense with the visual busy indicator and replace it by a busy relay operated by a local battery adjacent to the mechanism which would generate a tone signal to indicate the busy condition to any subscriber of the local group should the line be in use.

Similarly in the case of an ordinary party line subscriber the indicator shown might be replaced by one of a shutter type which is mechanically operated from the main shaft of the switches. By this means extra sensitivity would be obtained as the magnets F and C would not have to operate on the first pulse of a train in series with the winding of the indicator.

It should be mentioned also that further springs operated by the cams controlling the springs FWC and CWC could be arranged to disconnect the escapement magnets F and C when the switches were fully released and in this case the rectifiers NBC and MRD could be dispensed with.

Referring now to Figs. 1 and 2 it will be underof the large gear wheel H which is loosely supported'on the main shaft 12, and conveniently one end of the spring is secured to the wall of the cup while the other end is anchored to the I shaft [2.

Assuming that the mechanism is in the fully wound condition and that a subscriber originates a call, impulses generated at the exchange are received by the magnet F which rocks its armature [3 about the pivot I4 against the tension of 3 two flat restoring springs l5 and [6. An extenj sion of the armature of magnet F which co-operates with the escapement wheel I! is provided with a suitably forked end, capable of releasing the escapement wheel step by step as the armaf ture oscillates to produce a rotation of the shaft 12 in the direction indicated by the arrow. On

l the first step of the shaft to position 1, the projection on cam l8 leaves the operating roller l9 controlling the off-normal springs, as-a result of l which the off-normal springs are operated. Ro-

tation of the shaft continues under the control of the escapement and when the selecting posi- I tion for which this device is set is reached, the 1 projection on cam 20 lifts the roller 2| to operate the switching springs FI and F2.

In this position as will be remembered from the circuit description, the callingtelephone is connected'to the exchange equipment and the calling subscriber thereupon proceeds with the 1 setting up of the connection.

' At the conclusion of the call when the subscribers replace 7 their telephones, the release 3 pulses generated at the exchange are transmitted to the magnet F which thereupon releases 1 the escapement wheel step by step until the projectionon the cam 18 again lifts the roller 19 to f operate the off-normal springs which thereupon I short-circuit the magnet F by way of the rectif fier MRC shown in the circuit. The magnet F 1 therefore holds for the remainder of the releasingpulses and when they have ceased, de-energises 'and allows the escapement wheel to make one further step to position the roller 1 9 squarely on top of the cam.

By this time the collar 22 fastened to the extreme left hand end of the shaft 12 will have I made one complete revolution therewith and accordingly the pin it carries will come behind a 1 double pin passing through a loose cam plate 23 j shown more clearly in the plan View, thereby moving this cam plate one step and causing the roller 24 to ride out of a notchin the plate thus closing the winding cam springs FCW.

As'will ,be remembered from the circuit description, the winding magnet FW now operates in a self-interrupted circuit controlled by its interrupter springs 25 so that its armature oscillates about the pivot against the tension of the a restoring springs 26 and 21. reliable high speed operation, the interrupter In order to secure springs may if desired, incorporate a lost motion device toensure that the armature completes its 1 travel in both directions before the interrupter springs are actuated. Y

Pivoted to an extension ofthe winding magnet armature is a spring-loaded pawl 28 which cooperates'with the ratchet wheel 29 and by means of 'a forward drive operation, rotates the countershaft 30 in the direction indicated by the arrow. Also attached to the countershaft 30 is a gear wheel 3| in mesh with the large gear wheel H which it rotates in the direction indicated by the arrow, to wind up the driving spring contained in the cup I0. During each step of the windingmagnet .FW the countershaft is held in position by means of a detent 32 engaging with the ratchet wheel 29.

It has been found in practice that the winding can be accomplished in approximately five seconds and when it is completed the loose cam plate 23, which has been pushed round by a pin extending from the large gear wheel I I, again comes into its normal position. In this position the notch in its periphery is presented to the roller 24 which falls therein to open the springs FCW and disconnect the circuit to the winding magnet. The mechanism is now re-wound in readiness for a further operation. a

. In :order that the selecting cam'ZB may be I readily adjusted by hand to suit the number of the station with which it is associated, it is loosely supported on the shaft and coupled to the cam I8 by means of a pin extended from this cam (shown dotted) which enters the appropriate one of a number of, holes in the cam 20. Normally cam 20 is urged into engagement with cam 18 by means ofthe coil spring 33 encircling the shaft. Alteration to the setting of cam '20 is effected by moving it along the shaft until it disengages the pin on cam l8, then rotating it the desired amount and allowing it to re-engage the pin in the new position.

I claim:

1. In a telephone substation, a line, a movable member, a local source of energy urging said member in one direction, an escapement for said member controlled over the line to cause said source to' move said member step by step, and a circuit controlled by said member only when said member has been moved to a particular position by saidsource.

2. In a telephone substation, a line, a movable member, a local source of energy urging said member in onedirection, an escapement for said member controlled overthe line to cause said source to move said member step by step, and

a circuit normally disconnected from the line but connected thereto by said member when said member has been moved to a particular position by said source. 7 r r 3. In a telephone substation, a line, an electrical escapement comprising an escape wheel, a motor tending to rotate said wheel, and a pallet controlled overthe line to cause said motor to rotate said wheel step by step, a circuit normally disconnected from the line, and means controlled by said escapement for connecting said circuit to the line when the escape wheel has been rotated to a particular position. 7

4. In a telephone substation, a line, a motor, means operatedover said line to energize said motor, a movable member urged in one direction by said motor, an escapement for said member controlled by impulses transmitted over the line to cause said motor to move said member step by step, and a circuit controlled by said member only when said member has been moved to a particular position by said motor.

5; A'telephone substationas claimedin claim 4, wherein both the energization of said motor and the control of said escapement are intermittent, neither occurring at the same time as the other.

6. In a telephone substation, a line, a movable member, a motor having potential energy stored therein, means controlled over the line for utilizing the energy stored in the motor to drive said member step by step, and means operated at times by current received over the line to restore to said motor the energy expended in moving said member.

'7. A telephone system as claimed in claim 6, wherein said first means is controlled over one side of the line and wherein said last means is operated over the other side of the line.

8. A telephone system as claimed in claim 6, wherein said first means is controlled by impulses transmitted over the line, and wherein said last means is operated at times when said impulses are not being transmitted.

9. A telephone system as claimed in claim 6, wherein said last means is operated by current of one potential, and wherein said first means does notrespond to current of said one potential but is controlled by current of a different potential.

10. In a telephone substation, an escapement comprising a movable escape member, a spring for moving said member and a pallet for controlling the movement of said member, means including an electromagnet responsive to current of a, particular character received over the line for winding said spring, and means including another electromagnet responsive only to current of a difierent character received over the line for operating said pallet.

11. In a telephone substation, a line, a movable member, a motor with potential energy stored therein, means controlled over the line for utilizing the energy stored in said motor to drive said member, means operated when the energy stored in said motor has been reduced by a predetermined amount, and means rendered eifective by the operation of said last means and actuated by current received over the line for restoring to said motor the energy expended in driving said member.

12. In a substation as claimed in claim 11, means for automatically terminating the operation of said energy restoring means when the level of said motor is the same as it was before said motor was utilized to drive said member.

13. In a telephone substation, a line, a movable member, a motor with potential energy stored therein, means controlled over the line for utilizing the energy stored in said motor to drive said member to any of a plurality of positions, a circuit controlled by said member only when said member occupies a particular one of said positions, means operated when the energy stored in said motor has been reduced by a predetermined amount, and means rendered effective by the operation of said last means and actuated by current received over the line for restoring to said motor the energy expended in driving said member.

14. In a telephone substation, a line, a movable member occupying a particular position, a spring motor urging said member in one direction, an escapement controlled over the line to permit said motor to move said member step by step, means operated by said member when it has been moved a predetermined number of steps from said position, and winding means for said motor rendered efiective by the operation of said last means and actuated by'curre'n't received over the line.

1.5. A substation as claimed in claim 14, wherein said first means is effective to terminate the operation of said winding means after an interval to prevent said spring motor from being overwound.

16. In a telephone substation, a line, a movable member occupying a particular position, a spring motor urging said member in one direction, an. escapement controlled over the line to permit said motor to move said member step-bystep, a second member occupying a normal position and moved therefrom by said first member when. said first member has been moved a predetermined number of steps from said particular position, winding means for said motor rendered effective by the. movement of said second member from its, normal position and actuated by current received over the. line, said second member controlled by said winding means during the actuation thereof and restored to said normal position after the spring has been wound a predetermined amount, andmeans controlled by said second member' for terminating the actuation of said winding means responsive to the restoration of said second member to its normal position.

17. In combination, a line, an electrical blocking device having a resistance characteristic such. that when said device is subjected to an increasing potential its resistance decreases sharply after a. certain potential has been reached, an escapement comprising a movable member, a mechanical motor urging said member in one direction, and a pallet controlled over the line through said device by impulses of potential higher than said certain potential, and winding means for said motor controlled over saidv line byfa potential below said certain potential. 4

18, A combination as claimed in claim 17 wherein said device comprises a gaseous discharge device.

19. In a telephone system, a party line serving a plurality of stations, a movable member at each station, a local source of energy at each station tending to move said member, escapements for said members controlled in unison over the line, whereby said sources may move said members in unison to any of a plurality of positions, and a circuit at each station normally disconnected from said line but connected thereto by the member at that station when said member occupies a particular position, said particular position being different for difierent stations.

20. In a telephone system, a party line serving a plurality of stations, a motor at each station energized over the line, a movable member at each station urged in one direction by said motor, escapements for said members controlled in unison by impulses transmitted over the line to permit said sources to move said members step by step to any of a plurality of positions, a circuit controlling contact at each station actuated by said member only when said member occupies a particular position, said particular position being different for different stations.

21. In a telephone system, a party line serving a plurality of stations, each of said stations having thereat a movable member, a spring for moving said member and an escapement for controlling the movement thereof, said escapements controlled in unison by impulses transmitted and means including an electromagnetic stepby-step device at each station operated at times bycurrent transmitted over the'line to rewind the spring at that station. V 1

' 22. Atelephone system as claimed in claim 21,

wherein the current transmitted over the line for rewinding the spring is continuous, and wherein said step by step device operates intermittently by self-interruption of said current.

23. In a telephone system as claimed in claim 21, means at each station including a gaseous discharge device and an electromagnet connected to the line through said discharge device for controlling the escapement at that station, said discharge device preventing the operation of the escapement by current of the value transmitted to rewind the spring at that station.

24. In a telephone system, a party line serving a plurality of stations, each station having a step-by-step switch occupying a normal position and a circuit connected to the line only when said switch has been stepped from said normal position and occupies another particular position, said particular position being. difierent for diiferent-ones of said stations, each station also having a spring for moving the switch at that station and an escapement for controlling said movement, said es'capements' controlled in unison by impulses transmitted'over the line thereby to cause said switches to be moved in unison by their respective springs from said normal position to one of said particular positions, said escapements subsequently controlled in unison by impulses transmitted over the line thereby to cause said switches to be restored to their normal positions in unison by their respective springs, and means including an electromagnetic step-by-step device at each station operated by current transmitted over the line when the switches have been so restored to their normal positions for rewinding the. spring at that station.

amount for restoring said second member to its" normal position, and means controlled by said second member for terminating the actuation of said winding means responsive to the restoration of said second member to its normal position.

' 26.'In combination, a movable member, a source of energy moving said member, a second member having a normal position, means for displacing said second member from normal when said first member has been moved a certain distance by said source, means thereupon operated to add energy to said source and, when" a predetermined amount has been added, to restore said second member to normal, and means controlled by said second member for terminating the operationof said last means responsive to the restoration of said second member to normal. r

27. In combination, a motor, means for storing potential energy in said motor, a member at rest during said storing of energy in the motor and afterwards moved a certain distance by said motor whereby some of the stored energy is removed from the motor, means then effective to reoperate said storing means to restore to the motor the energy expended in movingsaid mem ber, and .means operated automatically when the nergy stored in the motor reaches an amount substantially equal to energy stored therei'n'before said movement of themember to terminate the operation of said storing means.

JOHN ST. CLAREWILLIAM GRAHAM. 

